“I’ve been fairly pointed in my comments that we’re in a space race with the Chinese, and that they are very good,” he said in a recent interview with The Washington Post. “Especially in the last 10 years, they’ve had a lot of success. They usually say what they mean, and they execute on what they say.”

But despite China’s many achievements in space — which include an occupied space station in low Earth orbit and landing a rover on Mars in 2021 — the United States remains on track to return astronauts to the lunar surface ahead of its chief rival, Nelson said.

NASA plans to one day build an enduring presence at the hottest real estate in the solar system: the lunar south pole. In a key step toward that goal, NASA intends to fly four astronauts around the moon late next year, and then land people on the surface in late 2026 for the first time since the last of the Apollo missions, in 1972.

“I think we are right on schedule,” Nelson said.

That schedule, however, has been pushed back a few times because of technical challenges, including an effort to better understand the performance of the heat shield of the capsule intended to fly astronauts to and from the vicinity of the moon. During a test flight around the moon in 2022 without anyone on board, the heat shield of NASA’s Orion spacecraft “wore away differently than expected” in more than 100 places as it plunged through the atmosphere, according to a report released in the spring by NASA’s inspector general. In some places, it looked like chunks were torn away, leaving pothole-like scars in the material.

“Should the same issue occur on future Artemis missions, it could lead to the loss of the vehicle or crew,” the report concluded.

NASA’s plan to return humans to the surface is a complicated one that requires Orion to get them to orbit around the moon, and then a separate spacecraft — SpaceX’s Starship — to transport them to the lunar surface. Starship would then fly the astronauts back to meet up with Orion in lunar orbit for the return trip back to Earth.

Given Starship’s important role of landing on the surface, NASA is closely watching its development. SpaceX recently conducted the fourth test flight of the massive vehicle, the biggest and most powerful ever built, flying it most of the way around the globe in what the company said was a largely successful flight that will allow it to continue to develop it rapidly.

Nelson said “a good indicator of” NASA’s ability to get to the moon ahead of China “was SpaceX’s success in their last Starship flight.” But Elon Musk’s company still needs to demonstrate the vehicle can be refueled in Earth orbit by a fleet of tanker spacecraft, fly humans safely as well as land softly on the moon — all highly ambitious, complicated tasks that could take years to achieve.

Both the U.S. and China are ultimately aiming to set up encampments by the moon’s south pole, where there is water in the form of ice in its permanently shadowed craters. Water is not only vital to sustain life, but its component parts, oxygen and hydrogen, can also be used as rocket fuel, allowing further exploration into the solar system.

Despite the competition between the U.S. and China, the two countries will have to find a way to coexist on and around the moon, Nelson said. The space programs of both countries are also bonded, he said, by threats in space.

U.S. officials have said that Russia is developing a nuclear weapon that could be used in Earth orbit to destroy satellites and cripple key U.S. national security infrastructure used for missile warnings, reconnaissance and to guide precision munitions, among other things. Russia has denied that it intends to deploy a nuclear weapon in space.

Still, it ought to concern all nations with assets in space, Nelson said, and especially China, which operates not only a growing number of spacecraft that could be disabled by a nuclear blast but a crewed space station as well.

Speaking publicly on the threat for the first time, he said: “All nations should be concerned that Russia may intend to put a nuclear weapon on orbit. Such a capability could pose a threat to all satellites operated by countries and companies around the globe, as well as to the vital communications, scientific, meteorological, agricultural, commercial and national security services that we all depend on.”

He added that “this is an opening for the Chinese government, whose Chinese astronauts and space station would be threatened by the deploying of a Russian nuclear bomb in space. … They have an interest in Russia not putting up nuclear weapons. So would they utilize their position with Russia and the relationship between [Chinese President] Xi Jinping and [Russian President Vladimir] Putin to urge the Russians to rethink this?”

An installation of a nuclear weapon on orbit would be a violation of the 1967 Outer Space Treaty. And as China and Russia continue to rival the U.S. in space, NASA and the State Department have sought to lead a growing international coalition under what is known as the Artemis Accords, perhaps the most significant international space policy effort since the 1967 treaty.

In an effort to put pressure on China’s space program, which Nelson and others have criticized as operating secretly and as an arm of the military, signatories to the accords agree to abide by accepted norms of behavior in space and on and around the moon. Countries would be required to share scientific discoveries, for example, and detail where they are operating on the lunar surface and what they are doing.

In the meantime, NASA’s lunar campaign continues. This year, the space agency hopes that one of its commercial partners, Intuitive Machines, a Houston company, will land its second uncrewed spacecraft on the moon, with other privately developed landers to follow in the years to come. Earlier this year, its spacecraft became the first commercial vehicle to land on the moon and the first American spacecraft to touch down softly since the Apollo era.

But for all the talk about a space race with China, the astronauts who are part of the planned Artemis mission to fly around the moon in 2025 said they don’t quite see it that way.

The commander of the flight, NASA astronaut Reid Wiseman, said during a recent Washington Post Live event that, “We don’t feel like this is a race. We feel like this is just the right direction for exploration, and that’s the direction we’re headed in.”

He added: “But as an American, I do sense that there is building pressure.”